1. Field of the Invention
This invention relates to truck mounted brake mechanisms for railway cars and more particularly to brake systems having means to increase the force applied by a hand brake to an actuating lever of the brake system.
2. Background and Objects of the Invention
Most railroad freight cars,use what is known as foundation brake rigging. On the car body, there is an air brake system which provides air to the brake cylinder, which, in turn, supplies a mechanical force, through a system of rods and levers to a connection on the standard freight car trucks located at each end of the car. At this point, the force is applied to a truck lever system, usually consisting of two levers and a connecting rod. The levers move Drake beams which apply force to the treads of the wheels through renewable friction blocks or brake shoes, retarding the rotation of the wheels.
One type of braking apparatus is shown and described in U.S. Pat. No. 4,312,428. In general, as illustrated in said patent, there is a manually operable mechanism connected to a lever of the air braking system for manually setting the brakes. The manually operable mechanism, also known as a "hand brake", usually comprises a manually rotatable wheel or a lever connected to reduction gears which rotate a chain drum for winding up a chain connected to a lever of the air braking system.
However, the manual force required to set-up the brakes is relatively high., and it is desirable to reduce such force. While the gear ratio could be changed, this requires additional activation of the hand wheel or lever and is relatively expensive.
One object of the invention is to increase the force applied to the brakes by the conventional hand brake driving mechanism without modifying the latter.
Another object of the invention is to reduce the forces on a support bracket which supports both a lever operable by the hand brake mechanism and a lever operated by the air braking apparatus.
Another object of the invention is to couple the hand brake driven lever to the brake actuating lever so that when the hand brake driven lever is in its release position, the air brake cylinder does not operate the hand brake mechanism.